1. Field of the Invention
The present invention relates to apparatus for protecting and preserving food, and especially for protecting hot food during transportation.
2. Description of Related Art
In recent years the business of delivering hot food to a home or business has grown dramatically. The current market for pizza delivery alone is estimated to comprise billions of dollars in business each year. Moreover, numerous other businesses depend upon individualized delivery of hot food, including catering businesses, various Asian, Mexican and other ethnic food restaurants, services providing hot meals to elderly and other shut-ins, services providing hot meals to schools and camps, etc.
In light of the active interest in such businesses, it is hardly surprising that tremendous activity has centered around means of keeping food hot (or cold) and fresh during transportation. The most common containers in this regard have been primary food packages constructed from waxed paper, plastic or cardboard. Although such containers are inexpensive and convenient, they have proven limited in their ability to preserve the temperature, freshness and texture of the food.
In response to these concerns, a number of solutions have been proposed. For example, delivered pizza today is commonly placed in a primary food receptacle (e.g. a cardboard box) and then inserted into an insulative pouch for transportation. These pouches are generally constructed from an outer shell of durable knit-backed vinyl or similar polymer material, insulated with approximately 11/4 inches of open cell foam on either side of the pizza box, and lined with a nylon coated with vinyl, or similar material.
In order to protect the insulation from becoming wet and/or contaminated with food, the interior liner is normally made water proof to contain moisture within the liner. It is generally recognized that the free flow of liquid through the liner presents a distinct health hazard by allowing bacteria to grow within the insulation and pass back to the food in condensed water vapor. Additionally, when foam insulation becomes wet, it loses its insulative properties and may even become a heat sink. To address these concerns, recent improvements in this area have included providing a liner of polyester MYLAR-type material which is both heat reflective and almost completely water and water vapor impermeable.
Although such pouches are convenient, relatively inexpensive, and a substantial improvement over the use of a box alone, they are deficient in many respects. The primary problem with these devices is that a sealed interior liner tends to trap moisture vapor given off by the food within the container itself. As the packaging begins to cool, this trapped moisture vapor condenses and leads to the pizza becoming "soggy." The addition of grommetted vent holes in the side of the pouch offers only limited improvement in these conditions. Vent holes free moisture vapor, but they simultaneously release heat-requiring careful proportions to permit liberating some steam while retaining a sufficiently hot and moist pizza. To compound this problem further, the loss of too much moisture is also to be avoided since it can result in the food becoming dry and unappetizing. As a result, these pouches are limited in their utility and service range and present a constant threat of cool and/or damp or dry pizza.
In light of these limitations, a number of far more exotic solutions have been proposed. U.S. Pat. No. 4,806,736 issued Feb. 21, 1989, to Schirico and U.S. Pat. No. 4,816,646 issued Mar. 28, 1989, to Greve each discloses use of pizza delivery containers containing built-in electric resistance heating elements to help keep pizzas hot. To address the problem of moisture build-up specifically, U.S. Pat. No. 4,922,626 issued May 8, 1990, to Fiddler discloses a pizza delivery container with a motor-driven fan to circulate moist air over a moisture-removing dissicant cartridge. These solutions may function reasonably well for their stated purposes, but they are each considered needlessly complicated and too cumbersome and expensive for widespread use.
Another area of growing interest is the delivery of relatively large quantities of hot foods. In addition to normal catering activities, a number of businesses have sought to expand into the delivery of large number of pizzas and other foods to schools and camps. In this context, the use of a relatively small pouch is simply impractical. Moreover, employing numerous pizza boxes or other primary food receptacles is considered both wasteful and a needless expense.
One solution proposed in this regard is to provide a rack in lo which multiple reusable trays of food can be stacked. To insulate the food in the rack, a padded nylon cover is formed around the rack to help contain the food heat. With a much greater quantity of food and much less relative outside surface area, food tends to stay warmer in this environment. Unfortunately, the problem of moisture build-up may be compounded since the amount of food contained in the rack is far greater than the available surface area permitting moisture dissipation. Additionally, if covered primary food receptacles are not employed in the food racks, there is also an increased risk of both liquid precipitating onto the food and bacterial contamination.
Finally, there are believed to be other applications where a breathable, insulated container for carrying perishables is of use. For example, in the transportation of certain bio-medical products and specimens it is sometimes desirable to keep the product at a constant temperature but allow the dissipation of moisture vapor without a build up of condensation.
Accordingly, it is a primary purpose of the present invention to provide an apparatus for protecting food and similar products which is effective at dissipating unwanted moisture vapor while retaining heat.
It is a further purpose of the present invention to provide such an apparatus which provides an effective barrier to liquid entering the storage area through either condensation or seepage from wet weather or other ambient conditions.
It is an additional purpose of the present invention to provide such an apparatus which can be adapted to control moisture effectively in a variety of applications, including instances where relatively large quantities of perishables must be protected.
It is another purpose of the present invention to provide such an apparatus which is relatively easy to construct, use, and transport.
These and other purposes of the present invention will become evident from review of the following specification.